None.
The present invention relates to an ultrasonic medical device, and more particularly to an apparatus and method for an ultrasonic medical device with improved visibility in imaging procedures for the detection inside of a body of an elongated probe comprising a material of high radiopacity;
Vascular occlusive disease affects millions of individuals worldwide and is characterized by a dangerous blockage of blood vessels. Vascular occlusive disease includes thrombosed hemodialysis grafts, peripheral artery disease, deep vein thrombosis, coronary artery disease and stroke. Vascular occlusions (clots, intravascular blood clots or thrombus, occlusional deposits, such as calcium deposits, fatty deposits, atherosclerotic plaque, cholesterol buildup, fibrous material buildup, arterial stenoses) result in the restriction or blockage of blood flow in the vessels in which they occur. Occlusions result in oxygen deprivation (xe2x80x9cischemiaxe2x80x9d) of tissues supplied by these blood vessels. Prolonged ischemia results in permanent damage of tissues which can lead to myocardial infarction, stroke, or death. Targets for occlusion include coronary arteries, peripheral arteries and other blood vessels. The disruption of an occlusion or thrombus can be affected by pharmacological agents and/or mechanical means. However, many thrombolytic drugs are associated with side effects such as severe bleeding which can result in a cerebral hemorrhage. Mechanical methods of treating thrombolysis include balloon angioplasty, which can result in ruptures in a blood vessel, and is generally limited to larger blood vessels. Scarring of vessels is common, which may lead to the formation of a secondary occlusion (a process known as restenosis). Another common problem is secondary vasoconstriction (classic recoil), a process by which spasms or an abrupt closure of the vessel occurs. These problems are common in treatments employing interventional devices. In traditional angioplasty, for instance, a balloon catheter is inserted into the occlusion, and through the application of hydraulic forces in the range of ten to fourteen atmospheres of pressure, the balloon is inflated. The non-compressible balloon applies this significant force to compress and flatten the occlusion, thereby opening the vessel for blood flow. However, these extreme forces result in the application of extreme stresses to the vessel, potentially rupturing the vessel, or weakening it thereby increasing the chance of post-operative aneurysm, or creating vasoconstrictive or restenotic conditions. In addition, the particulate matter is not removed, rather it is just compressed. Other mechanical devices that drill through and attempt to remove an occlusion have also been used, and create the same danger of physical damage to blood vessels.
Ultrasonic probes using ultrasonic energy to fragment body tissue have been used in many surgical procedures (see, e.g., U.S. Pat. No. 5,112,300; U.S. Pat. No. 5,180,363; U.S. Pat. No. 4,989,583; U.S. Pat. No. 4,931,047; U.S. Pat. No. 4,922,902; and U.S. Pat. No. 3,805,787). The use of ultrasonic energy has been proposed both to mechanically disrupt clots, and to enhance the intravascular delivery of drugs to clot formations (see, e.g., U.S. Pat. No. 5,725,494; U.S. Pat. No. 5,728,062; and U.S. Pat. No. 5,735,811). Ultrasonic devices used for vascular treatments typically comprise an extracorporeal transducer coupled to a solid metal wire which is then threaded through the blood vessel and placed in contact with the occlusion (see, e.g., U.S. Pat. No. 5,269,297). In some cases, the transducer, comprising a bendable plate, is delivered to the site of the clot (see, e.g., U.S. Pat. No. 5,931,805).
The ultrasonic energy produced by an elongated probe is in the form of very intense, high frequency sound vibrations that result in physical reactions in the water molecules within a body tissue or surrounding fluids in proximity to the probe. These reactions ultimately result in a process called xe2x80x9ccavitation,xe2x80x9d which can be thought of as a form of cold (i.e., non-thermal) boiling of the water in the body tissue, such that microscopic bubbles are rapidly created and destroyed in the water creating cavities in their wake. As surrounding water molecules rush in to fill the cavity created by collapsed bubbles, they collide with each other with great force. Cavitation results in shock waves running outward from the collapsed bubbles which can wear away or destroy material such as surrounding tissue in the vicinity of the elongated probe.
Some ultrasonic devices include a mechanism for irrigating an area where the ultrasonic treatment is being performed (e.g., a body cavity or lumen) in order to wash tissue debris from the area of treatment. Mechanisms used for irrigation or aspiration described in the art are generally structured such that they increase the overall cross-sectional profile of the elongated probe, by including inner and outer concentric lumens within the probe to provide irrigation and aspiration channels. In addition to making the probe more invasive, prior art probes also maintain a strict orientation of the aspiration and the irrigation mechanism, such that the inner and outer lumens for irrigation and aspiration remain in a fixed position relative to one another, which is generally closely adjacent to the area of treatment. Thus, the irrigation lumen does not extend beyond the suction lumen (i.e., there is no movement of the lumens relative to one another) and any aspiration is limited to picking up fluid and/or tissue remnants within the defined area between the two lumens.
As discussed above, medical devices utilizing ultrasonic energy to destroy biological material in the human body are known in the art. A major drawback of existing ultrasonic devices comprising an elongated probe for biological material removal is that they are relatively slow in comparison to procedures that involve surgical excision. This is mainly attributed to the fact that such ultrasonic devices rely on imparting ultrasonic energy to contacting biological material by undergoing a longitudinal vibration of the probe tip, wherein the probe tip is mechanically vibrated at an ultrasonic frequency in a direction parallel to the probe longitudinal axis. This, in turn, produces a biological material destroying effect that is entirely localized at the probe tip, which substantially limits its ability to ablate large biological material areas in a short time. An ultrasonic medical device with a multiple material coaxial construction for conducting axial vibrations is known in the art (see, e.g., U.S. Pat. No. 6,277,084). In addition to prior art ultrasonic devices being slow, previous ultrasonic methods of treating plaque still include many undesirable complications and dangers.
The inability to detect the location of an ultrasonic probe during a medical procedure deep in a body has not been solved by the prior art. Prior art ultrasonic probes are typically comprised of a high capacitance material. Often, such high capacitance materials have a low radiopacity. Low radiopacity materials allow the passage of x-rays or other radiation. Because these high capacitance materials do not absorb enough radiation, a user is unable to locate the exact position of the ultrasonic probe inside the human body during a medical procedure which includes an imaging procedure.
Imaging procedures typically include fluoroscopy or radiography. Fluoroscopy is a method of viewing the interior of the body, which would be opaque to longer wavelength electromagnetic radiation, in which a continuous x-ray beam is passed through the body part being examined, and is transmitted to a television-like monitor so that the body part and its motion can be seen in detail. Fluoroscopy is used in many types of examinations and procedures, such as barium x-rays, cardiac catherization, and placement of intravenous (IV) catheters (hollow tubes into veins or arteries). Radiography is a procedure that uses standard x-rays to analyze the bony and soft tissue anatomy for diagnosis.
Prior art attempts to visualize materials in a human body during a medical procedure have been less than successful. For example, U.S. Pat. No. 5,824,042 to Lombardi et al. discloses an endoluminal prosthesis for deployment in a lumen of a patient""s body, the prosthesis comprising a tubular fabric liner and a radially expandable frame supporting the liner. A plurality of imagable bodies are attached to the liner, the imagable bodies providing a sharp contrast so as to define a pattern which indicates the prosthesis position when the prosthesis is imaged within the patient body. Lombardi et al. requires the plurality of imagable bodies to be stitched into tubular fabric liner; the plurality of imagable bodies could not be stitched into an ultrasonic probe. The plurality of imagable bodies disclosed in Lombardi et al. would not be able to withstand vibrations of an ultrasonic device. Therefore, a need remains in the art for an apparatus and method of visualizing the position of an ultrasonic probe during a medical procedure which includes an imaging procedure.
U.S. Pat. No. 5,622,170 to Schulz discloses a system for sensing at least two points on an object for determining the position and orientation of the object relative to another object. Two light emitters mounted in spaced relation to each other on an external portion of an invasive probe, remaining outside an object into which an invasive tip is inserted, are sequentially strobed to emit light. In Schulz, a computer determines the position and orientation of the invasive portion of the probe inside the object by correlating the position of the invasive portion of the probe relative to a predetermined coordinate system with a model of the object defined relative to the predetermined coordinate system. Schulz does not allow for the position of the probe to be determined directly but rather provides a representation of the probe""s position relative to a predetermined coordinate system. Also, Schulz discloses an expensive, complicated and complex method of approximating the position of a probe once inside a body. Therefore, a need remains in the art for an apparatus and method of visualizing the position of an ultrasonic probe during a medical procedure which includes an imaging procedure.
U.S. Pat. No. 5,588,432 to Crowley discloses an acoustic imaging system for use within a heart comprising a catheter, an ultrasound device incorporated into the catheter, and an electrode mounted on the catheter. In Crowley, a central processing unit creates a graphical representation of the internal structure, and superimposes items of data onto the graphical representation at locations that represent the respective plurality of locations within the internal structure corresponding to the plurality of items of data. Like Schulz, Crowley does not allow for the position of the medical device to be determined directly, but rather provides a representation of the device""s position corresponding to the plurality of items of data. Therefore, a need remains in the art for an apparatus and a method of visualizing the position of an ultrasonic probe during a medical procedure which includes an imaging procedure.
Other attempts to improve the detection of a device used in a medical procedure that includes an imaging procedure include attaching a number of metal bands or the use of the device in conjunction with a barium-filled catheter. Although such devices may improve the ability to detect a material that is not easily visible, they are difficult to use in conjunction with an ultrasonic probe because the metal bands are difficult to attach to an ultrasonic probe and can separate from the ultrasonic probe due to vibration of the ultrasonic probe. A barium-filled catheter allows for improved detection of the catheter, but does not allow for the exact location of the ultrasonic probe to be determined. Also, barium-filled catheters are known in the art to obstruct the ability to view surrounding arteries and veins. Therefore, a need remains in the art for an apparatus and a method of better visualizing the position of an ultrasonic probe during a medical procedure that includes an imaging procedure.
Other attempts at improving the ability to detect a device inside the body include using a high-vacuum deposition process that results in a thin-film coating. Traditional ion-beam-assisted deposition (IBAD) employs an electron-beam evaporator to create a vapor of atoms that coats the surface of the device. A similar process known as microfusion comprises placing the substrate to be coated between two magnetrons. Provision is made for an adjustable bias to be applied to the substrate, as required, to control ion energy and flux. The prior art processes are complex, difficult to implement, and expensive. Therefore, a need remains in the art for a simple and inexpensive apparatus and a method of detecting the position of an ultrasonic probe during a medical procedure that includes an imaging procedure.
The prior art devices and methods of visualizing an ultrasonic probe inside a body are complex, complicated and expensive. Therefore, there is a need in the art for an apparatus and method for an ultrasonic medical device with improved visibility in imaging procedures that is simple, user-friendly, reliable and cost effective.
The present invention provides an apparatus and method for an ultrasonic medical device with improved visibility in imaging procedures. Imaging procedures include, but are not limited to, fluoroscopy, radiography, tomography, digital x-ray imaging, ultrasound and magnetic resonance imaging (MRI).
The present invention is a medical device comprising an elongated probe having a material of high radiopacity at an at least one predetermined location of the elongated probe wherein the material of high radiopacity is capable of withstanding a series of vibrations of the elongated probe. In a preferred embodiment of the present invention, the material of high radiopacity is at a distal end of the elongated probe and allows the elongated probe to be visualized in imaging procedures.
The present invention is an elongated probe comprising a material of low radiopacity and a material of high radiopacity that allows the medical device to benefit from the high capacitance properties of the material of low radiopacity and the ability of the material of high radiopacity to absorb radiation to allow the elongated probe to be visualized during a medical procedure which includes an imaging procedure. The material of high radiopacity is biocompatible and non-toxic and is selected from a group including, but not limited to, tantalum, tungsten, gold, molybdenum and alloys thereof.
The present invention is an apparatus comprising a small diameter elongated probe having a material of high radiopacity. The small diameter of the elongated probe allows for facile insertion of the elongated probe into a body. The material of high radiopacity allows for detection of the elongated probe when used inside a body during a medical procedure which includes an imaging procedure.
The present invention also provides a method of improving the visibility of an ultrasonic device during a medical procedure by engaging a material of high radiopacity to a small diameter elongated probe at an at least one predetermined location. The material of high radiopacity is engaged to the elongated probe by processes including, but not limited to, butt-welding, brazing, shrink fitting, lap welding, threaded fitting, twisting the materials or other mechanical or metallurgical connections.
The present invention is a medical device comprising an elongated probe having a material of high radiopacity at a plurality of locations of the elongated probe. The present invention provides an ultrasonic medical device with improved visibility in imaging procedures that is simple, user-friendly, reliable and cost effective.